1. Field of the Invention
This invention relates to thermal engines and, more particularly, to a method for controlling the speed of rotation of a thermal engine.
2. Description of the Prior Art
Among major performance characteristics of a machine equipped with a thermal engine are: reliability, capacity, fuel efficiency, ability to perform process operations, the amount of fumes and toxicity of exhaust gases at transient operating conditions, and other ratings. To a substantial extent these ratings depend on the manner in which the rotational speed of the thermal engine is controlled at transient operating conditions, particularly those involving overcontrol and duration of the transient process.
There is known a method for controlling the rotational speed of a thermal engine embodied in a speed governor described in SU, A, 217,218. In this method a signal is shaped for controlling the speed of rotation of an electric motor energized by a current source connected to a control circuit of the electric motor, and a correction signal is formed for correcting the rotational speed of the electric motor at transient operating conditions proportional to the deviation in the position of the outlet shaft of the differential mechanism which is kinematically linked with the fuel meter of the thermal engine. A feedback potentiometer secured at the speed control lever ensures inclination of the control characteristic of the speed of rotation of the thermal engine.
Shaping a control signal in the form of a rigid feedback, involving the differential mechanism and electric motor, imparts to the control characteristic a static feature normally improving the control over the rotational speed of the thermal engine. However, at inclinations of the control characteristic of the thermal engine normally not exceeding 6-8% of the rated rotational speed of the thermal engine, highly efficient control over the speed of rotation of the thermal engine is not ensured.
There is also known a method for controlling the speed of rotation of a thermal engine materialized in a speed regulator disclosed in Su, A, 708,065. In this method the speed of rotation is preset, a control signal corresponding to this speed is shaped for controlling the rotational speed of an electric motor based on the speed of rotation of one of the input shafts of the differential mechanisms kinematically linked with the electric motor and with the thermal engine whose fuel meter is kinematically linked with the output shaft of the differential mechanism, and simultaneously a correction signal is shaped for correcting the rotational speed of the electric motor at transient operating conditions.
The correction signal is shaped to be proportional to the derivative of the speed of rotation of the input shaft of the differential mechanism which is kinematically linked with the thermal engine.
As compared with the method previously described, this prior art method affords a higher stability and efficiency of speed controlling, such as overcontrol magnitude and duration of the transient operation period, through shaping a correction signal in the form of a derivative of the speed of rotation of the thermal engine. However, when shaping the correction signal as a derivative of the speed of rotation, this signal fails to follow deviation in the speed of rotation of the thermal engine in the course of controlling, whereby high speed-control efficiency cannot be attained.